Molecular Analysis of Anthocyanin Biosynthetic Genes and Control of Flower Coloration by Flavonoid 3′,5′-Hydroxylase (F3′5′H) in Dendrobium moniliforme

Abstract

Dendrobium moniliforme is a native species of Korea. The flower of this species is composed of a reproductive column and white perianths including petals, sepals and lip, but the base of the column bears reddish purple pigment spots. Anthocyanins are major pigments that contribute flower color in Dendrobium. Three key anthocyanin biosynthetic genes encoding dihydroflavonol 4-reductase (DFR), chalcone synthase (CHS), and flavonoid 3',5'-hydroxylase (F3'5'H) were isolated and analyzed for their expression patterns in floral organs to understand the molecular mechanism underlying flower color development. Quantitative RT-PCR analysis revealed that F3'5'H transcripts were highly accumulated in the base of the column compared with those of perianths, but the other two genes showed no significant difference among the floral organs. Microprojectile bombardment using the white perianths revealed that the transient expression of F3'5'H gene, but not DFR and CHS genes, was sufficient to produce reddish purple colored pigmentation. These results suggest that the lack of colors in perianths of D. moniliforme is at least due to transcriptional control of F3'5'H. The data presented here may improve our understanding of the mechanisms underlying floral color development in D. moniliforme and contribute to advances in orchid biotechnology.